Patent GB-401338-A (GB)
Title: Improvements in the colouration of textile materials made of or containing cellulose esters or ethers
IPC: D06P3/44
Filed: 1932-05-04
Abstract: Cellulose esters or ethers, dyeing; azo dyes, forming on the material; printing.--Dischargeable full black dyeings are produced upon cellulose esters or ethers in textile materials made of or containing them by applying a dischargeable yellow, orange and/or red dyestuff having affinity for cellulose esters or ethers and resistant to diazotization, applying also a diazotizable base having affinity for cellulose esters or ethers and yielding navy blue or thin black shades upon diazotization and development, and thereafter effecting such diazotization and development.  The proportion of diazotizable base used must be such as would not, in the absence of the yellow, orange or red dyestuff, yield full black shades.  Specified diazotizable bases are p-aminobenzene-azo-dimethylaniline and other p-aminobenzene-azo-dialkyl-, alkylaryl- or alkylaralkyl-anilines, benzene-azo-a -naphthylamine or naphthalene-azo-a -naphthylamine or nuclear substitution products thereof such as o - methoxy - or o-ethoxy-benzene-azo-a -naphthylamine, 4 : 4<1>-diaminoazobenzene, dianisidine and similar diamines yielding blue to black shades when diazotized and coupled with b -naphthol or 2 : 3-oxynaphthoic acid. Specified yellow, orange or red dyestuffs are benzene-azo-benzene-azo-phenol, benzene-azo-naphthalene-azo-phenol and 4-nitro-2-methoxybenzene-azo-dimethyl- or -diethyl-aniline.  The bases and/or the dyestuffs may be applied by dispersion methods, e.g. by the methods of Specifications 219,349, 224,925, 242,393, 242,711, 269,960, 273,819, 273,820, 322,737, and 323,788, [all in Class 15 (ii), Dyeing, Processes &c. for].  They may be applied by dyeing, padding, all-over printing or by localized printing or stencilling methods and the coupling component may be applied simultaneously or in a separate bath.  The full black shades are dischargeable by reducing discharging agents such as zinc formaldehydesulphoxylate or Decroline (Registered Trade Mark). Such agents may be applied in conjunction with swelling or softening agents for the cellulose esters or ethers, such as diethyleneglycol, triethyleneglycol or thiodiglycol with or without an admixture of ethyl lactate as in the process of Specification 400,643.  Coloured discharges are obtainable, e.g. by incorporating in the discharge pastes the pyrazolone dyestuffs of Specifications 346,751 and 380,061.  The following examples are specified.  (1) A cellulose acetate fabric is dyed with aqueous dispersions of 0.60 per cent of p-aminobenzene-azo-dimethylaniline, 0,36 per cent. of benzene-azo-benzene-azo-phenol and 0,04 per cent of 4-nitro-2-methoxybenzene-azo-dimethylaniline, based on the weight of the fabric, and the dyed fabric is subjected to diazotization and development with 2 : 3-oxynaphthoic acid; the fabric is then printed with a discharge paste containing Decroline (Registered Trade Mark), diethyleneglycol, ethyl lactate and gum arabic, dried, aged, washed and finished to obtain a white discharge on a full black ground.  (2) A cellulose acetate fabric is dyed with aqueous dispersions of 0,5 per cent of p-amino-azo-benzene-N-methyldiphenylamine and 0,2 per cent of benzene-azo-naphthalene-azo-phenol, based on the weight of the fabric, and the dyed fabric is subjected to diazotization and development with 2 : 3-oxynaphthoic acid; the fabric is then printed with a discharge paste containing zinc formaldehydesulphoxylate, diethyleneglycol, ethyl lactate, p-acetoxybenzene-azo-phenylmethylpyrazolone and gum arabic, dried, steamed, washed, dried and finished to obtain a bright yellow discharge on a full black ground.  (3) A cellulose acetate fabric is dyed with 0,6 per cent of o-methoxybenzene-azo-a -naphthylamine, 0,1 per cent of benzeneazonaphthalene-azo-phenol and 0,08 per cent of 4-nitro-2-methoxybenzene-azo-dimethylaniline, based on the weight of the fabric, and the dyed fabric is diazotized and developed with 2 : 3-oxynaphthoic acid; the fabric is then printed with a discharge paste containing zinc formaldehydesulphoxylate, diethylene glycol, ethyl lactate and gum arabic, dried, aged, washed and dried to obtain a parchment white discharge on a full black ground.